1. Field of the Invention
The present invention relates to a novel amino acid derivative having an excellent active oxygen resistance and exhibiting a good solubility, and an active oxygen-resisting agent comprising the same as an active ingredient.
2. Description of the Related Art
In recent years, various skin disorders and diseases owing to active oxygen species have been reported. For example, it has been known that in aging, canceration, pigmentation and inflammation of the skin by sunlight, especially, ultraviolet light, an active oxygen species deeply participates therein as the cause thereof. Accordingly, if the action of the active oxygen species can be inhibited, it is expected that these disorders and diseases of the skin can be prevented.
Enzymatic antioxidants including superoxide dismutase (SOD), non-enzymatic antioxidants such as ascorbic acid, tocopherol or glutathione, or antioxidant derived from a vegetables, such as tannin are known as substances that inhibits the action of an active oxygen species. However, of these substances, the use of SOD is limited because it is costly and chemically unstable. Also the non-enzymatic antioxidants such as ascorbic acid, tocopherol or glutathione are unstable in many cases, and their effect of inhibiting the active oxygen species is unsatisfactory. The antioxidants derived from the vegetables, such as tannin, are also easily hydrolyzed, and themselves easily oxidized. Accordingly, these substances are problematic in stability in many cases.
Further, in recent years, some investigations have been reported in which a metal ion present in vivo plays a part as a catalyst in the occurrence of the active oxygen species, the occurrence of the active oxygen species is controlled by chelation of the metal ion (for example, Free Radicals in Biology and Medicine, Oxford, Clarendon Press, p. 234, 1989). As a compound having a chelation ability, a disferrioxamine compound is known. Since this compound is, however, too strong a chelator, the balance of the metal ion in vivo is interfered with, and this compound is costly. Besides the disferrioxamine compound, metal ion chelating agents such as 2,2'-dipyridyl, 1,10-phenanthrolene and 2,2'-dipyridylamine have been studied. However, most of these compounds exhibit skin irritation.
Amino acid derivatives which are stable, which show low skin irritation and which have an excellent active oxygen resistance are reported in WO 94/14755 (U.S. Pat. No. 5,594,012). Nevertheless, since the derivatives have a low solubility in a multi-purpose oil solvent such as liquid paraffin or an olive oil, the use thereof is limited.